A p chart is used to monitor the fraction defective of an integrated circuit to be used in a commercial pacemaker. A sample of 15 circuits is taken from each day’s production for 30 consecutive working days. A total of 17 defectives are discovered during this period.

a. Determine the three-sigma control limits for this process.

b. Suppose that , the probability of Type 1 error (that is, the probability of drawing the conclusion that the process is out of control when it is in control), is set to be

.05. What control limits do you now obtain? (Use a normal approximation for your calculations.)